Function getFormatExpressionLocale

packages/common/src/utils/formatting.ts:599–608

(
    item:
        | Field
        | AdditionalMetric
        | TableCalculation
        | CustomDimension
        | undefined,
)

// expressions the same way formatItemValue does. Returns undefined for the
// default/US separator so output stays byte-identical.
export function getFormatExpressionLocale(
    item:
        | Field
        | AdditionalMetric
        | TableCalculation
        | CustomDimension
        | undefined,
): string | undefined {
    return separatorToNumfmtLocale(getEffectiveSeparator(item));
}

export function getCustomFormat(
    item: